Verses with the word certainty in the New Testament (3 verses):

Luke 1:4
That thou mightest know the certainty of those things, wherein thou hast been instructed.

Acts 21:34
And some cried one thing, some another, among the multitude: and when he could not know the certainty for the tumult, he commanded him to be carried into the castle.

Acts 22:30
On the morrow, because he would have known the certainty wherefore he was accused of the Jews, he loosed him from his bands, and commanded the chief priests and all their council to appear, and brought Paul down, and set him before them.